Python:Code Taka第2週4

Q.numsは数字からなる配列です。最もよく現れる数字をk個返してください。

nums = [1,1,1,2,2,3],
k = 2

return [1,2]

nums = [1]
k = 1

return [1]

私の答え

from collections import Counter
def top_k(nums, k):
  cnt = Counter(nums)
  top = cnt.most_common()
  result = []
  for n in range(k):
      result.append(top[n][0])
  
  return result

もう少し簡単に直した答え

from collections import Counter

def top_k(nums, k):
  cnt = Counter(nums)
  top = cnt.most_common(k)
  return list(map(lambda x: x[0], top))

ソリューション

def top_k(nums, k):
    count = {}
    for n in nums:
        count[n] = count.get(n, 0) + 1
        
    bucket = [[] for _ in range(len(nums)+1)]
    
    for n, freq in count.items():
        bucket[freq].append(n)
        
    ret = []
    for n_list in bucket[::-1]:
        if n_list:
            ret.extend(n_list)
            if len(ret) == k:
                return ret